Field of the Invention
The present invention relates to a connector attached optical fiber unit in which a plurality of optical fibers having tip portions inserted into and fixed to an MT optical connector pass inside a boot attached to the MT optical connector, and an optical connector boot which is suitably used for the boot of the connector attached optical fiber unit.
Priority is claimed on Japanese Patent Application No. 2014-111242, filed on May 29, 2014, the content of which is incorporated herein by reference.
Description of Related Art
An MT optical connector (based on F12 type optical connector of ESC 5981 and MT: Mechanically Transferable) is known as a multi-core optical connector which can cover the end of an optical fiber tape (a tape-like multi-core optical fiber such as an optical fiber tape core wire) so as to be connectable by a connector.
The MT optical connector (hereinafter, also referred to as an MT connector) includes a plastic body of which the outline is formed in an approximately rectangular plate shape. In the MT connector, a butting-joining front end surface (hereinafter, referred to as a joining end surface), a window hole which is recessed from one of the connector, and a boot hole which extends from the window hole to the connector rear side and is opened to a connector rear end surface are formed.
Moreover, in the MT connector, a plurality of fiber positioning holes which penetrate a front wall portion positioned at the front side from the window hole in a frontward-rearward direction in a connector and which are micro-pores opened to the joining end surface and the window hole are formed.
When the MT connector is attached to the optical fiber tape tip portion, the optical fiber tape tip portion is inserted into the window hole from the connector rear side via the boot hole and is adhesively fixed to the body by adhesive filling the window hole. The tip portion of the optical fiber tape is inserted from the boot hole in a state where a coating material is removed in advance and a plurality of bare optical fibers are exposed, and the bare optical fibers are inserted into the fiber positioning holes of the connector front wall portion one by one.
In addition, during an operation in which the MT connector is attached to the optical fiber tape tip portion, an operation is widely performed in which a tubular boot externally inserted into the optical fiber tape is inserted into the boot hole of the MT connector and is adhesively fixed to the body by the adhesive filling the window hole. A portion which protrudes rearward from the MT connector is provided in the boot.
The boot is made of a resin having flexibility such as elastomer. When a bending force is applied to the optical fiber tape, the portion of the boot which protrudes from the MT connector toward the rear side is bent according to the flexibility thereof, and thus, the optical fiber tape in the vicinity of the connector rear end surface is prevented from being bent to a small bending radius below an allowable bending radius at which the optical transmission characteristics of the optical fiber tape can be maintained.
In general, the boot hole of the MT connector is an angular hole having a rectangular cross-sectional shape which is thin and long in the longitudinal direction of the rectangular connector rear end surface. Generally, the outer circumferential surface of the boot is formed in a flat tubular shape which approximately coincides with the inner circumferential surface of the boot hole (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2005-099477). A through hole inside the boot is formed to extend in a slender flat cross-section along a cross-sectional longitudinal direction of the boot (hereinafter, referred to as the boot width direction). The optical fiber tape passes inside the boot so that the cross-sectional longitudinal direction of the optical fiber tape is arranged in the cross-sectional longitudinal direction of the through hole inside the boot.
In addition, the boot with the flat tubular shape is also disclosed in Japanese Unexamined Patent Application, First Publication No. 2009-230105.